Calling Java from Delphi via JNI

Question

Hi all. I've got a J2EE application, and I'm trying to write a Delphi client for the server. More specifics:
Server and test client running in Win2000 SP4.
Server running in JBoss (JUnit test cases have successfully connected to the server)
JDK 1.4
I'm using some Delphi files from JEDI which allow me to load/access a JVM via JNI. So far, I've been able to:
1) Create a Properties object.
2) Populate the Properties object with String values (making sure to use NewStringUTF to pass into the Properties method
3) Find my java client classes which facilitate opening a connection.
However, when I attempt to call the method on the object which actually creates the connection, I get an Exception.
My immediate question is how do I see what the Exception is? I have an Exception object, but ExceptionDescribe doesn't product anything, and I'm having trouble finding any details about the Exception (what type of exception, what the Message or Call Stack is). At the moment, something's wrong but I can't see what. And I'll have no chance of fixing it if I don't know what the problem is.
Thanks for any help,
Ed

Answer 1

I use some code for solving this task (in real project with Delphi 6.0 & Java 1.4.1).
May be, it will help.
procedure TJavaInterp.CheckJNIException(Message : string);
begin
if JNI_ExceptionCheck(JNIEnv) = JNI_TRUE then
begin
JNI_ExceptionDescribe(JNIEnv);
JNI_ExceptionClear(JNIEnv);
raise Exception.Create(Message);
end;
end;{ TJavaInterp.CheckJNIException }
procedure TJavaInterp.HandleException(excpt : jthrowable);
var
Msg: string;
ESyntax : Exception;
CauseName : WideString;
Tag : OleVariant;
begin
if JNI_IsInstanceOf(JNIEnv, excpt, FclsCommonSyntaxError) = JNI_TRUE then
begin
ESyntax := Self.BuildSyntaxException(excpt);
JNI_DeleteLocalRef(JNIEnv, excpt);
raise ESyntax;
end;
Msg := Self.GetMessage(excpt);
if JNI_IsInstanceOf(JNIEnv, excpt, FclsNPScriptRuntimeException) = JNI_TRUE then
begin
CauseName := Self.GetCauseName(excpt);
Tag := Self.GetTag(excpt);
JNI_DeleteLocalRef(JNIEnv, excpt);
raise NPScriptHelper.BuildNPScriptRuntimeException(Msg, CauseName, Tag);
end;
if JNI_IsInstanceOf(JNIEnv, excpt, FclsHaltException) = JNI_TRUE then
begin
JNI_DeleteLocalRef(JNIEnv, excpt);
raise Exception.Create(Msg);
end;
Msg := Self.ToString(excpt);
JNI_DeleteLocalRef(JNIEnv, excpt);
raise Exception.Create(Msg);
end;{ TJavaInterp.HandleException }